The present invention relates to a controller for a brushless motor that determines differences between target currents and detected currents in a dq coordinate system and determines a target voltage applied to an armature winding based on a feedback calculation, such as PI (Proportional Integral) calculation, P (Proportional) calculation, or PID (Proportional Integral Derivative) calculation, to decrease the differences.
A conventional controller for a brushless motor comprises a current detection part that detects currents flowing in the armature winding, a rotation position detection part that detects a rotation position of a rotor of the motor, a dq-axes target current calculation part that calculates a d-axis target current and a q-axis target current, a dq-axes current calculation part that determines a d-axis current and a q-axis current based on the detected currents and the detected rotation position, a d-axis target voltage calculation part that determines a d-axis target voltage based on the PI calculation for the d-axis current so as to decrease a d-axis difference between the d-axis target current and the d-axis current, and a q-axis target voltage calculation part that determines a q-axis target voltage based on the PI calculation for the q-axis current so as to decrease a q-axis difference between the q-axis target current and the q-axis current, in which the controller generates the rotation force of the rotor by applying the voltage to the armature winding based on the d-axis target voltage, q-axis target voltage, and the detected rotation position (Japanese Patent Application Laid-open No. 2001-187578).